1. Field of the Invention
The present invention relates to a control system for various machines used in construction sites, and more particularly, it relates to a control system for construction machines that are incorporated with an elevation measuring apparatus having a rotary laser apparatus and an optical sensor in combination, and also with a horizontal 2-dimensional position measuring apparatus used in combination with a GPS receiver.
2. Prior Art
In order to use graders and bulldozers to level or shape the ground for preparing residential areas and paving roads, there is a need for a system that is capable of determining positions of such machines in horizontal plane and elevations of lands required to level. For recent years, a construction machine control system has been developed where a GPS system determines a position of a construction machine in horizontal plane while a rotary laser apparatus determines an elevation of the terrain under construction, so as to control the construction machine. In such a system, the rotary laser apparatus predetermines a reference elevation on which the construction machine may be manipulated.
Referring to FIG. 47, the state-of-the-art construction machine system will now be described. In FIG. 47, an application of the system to a bulldozer is depicted. A construction machine control system 900 is comprised of a rotary laser apparatus 951 and a bulldozer 902 having a laser sensor 907 mounted therein. The rotary laser apparatus 951 is topped on a tripod 903 settled in position. The rotary laser apparatus 951 emits laser beam 904 horizontally, having the laser beam 904 circularly sweep to define a reference plane of the laser beam.
The bulldozer 902, which is used to level and shape the ground, has a blade 905 attached thereto and vertically movable. A level sensor 907 is fixed to a pole 906 that is coupled to the blade 905. The level sensor 907 receives the laser beam 904 emitted from the rotary laser apparatus 951 and then detects a current elevation of the level sensor 907. The bulldozer 902 includes a control device (not shown). The control device (not shown) obtains the detected elevation from the level sensor 907 and then computes an altitude of the blade 905 based upon the obtained elevation to adjust the blade 905 up or down to the desired level.
As has been described, the laser beam 904 defines the horizontal reference plane, and hence, controlling a distance between the horizontal reference plane and an edge 905a of the blade 905 to keep it constant, the land can be bulldozed and leveled. Varying the distance between the horizontal reference plane and the blade edge 905a, it is also possible to level the land in terraced terrain.
With reference to FIG. 48, determination of a position of the bulldozer in the horizontal plane will be described. For the purpose of determining the position of the bulldozer 902 in the horizontal plane, a GPS is used. First, a GPS base antenna 908 is placed in a known position. An additional GPS antenna 909 is mounted on the bulldozer 902. The GPS base antenna 908 receives radio waves from a satellite 910 to detect where the GPS base antenna 908 positions itself. Similarly, the GPS antenna 909 receives radio waves from the satellite 910 to detect where the GPS antenna 909 positions itself. Comparing the detection results, a relative position of the GPS base antenna 908 to the GPS antenna 909 is computed. The known position of the GPS base antenna 908 and the computed relative position are used to further compute a position of the bulldozer 902. Based upon the resultant position of the bulldozer 902, the leveling task is performed within the required range.
Typically, more than one construction machines are used to level the identical region unless the construction site is relatively small in dimensions. As is often the case, the construction machines simultaneously level the land up or down to create sections at different elevations. In this situation, the construction machines should individually have their respective rotary laser apparatus operated to sense elevations. Simultaneous activation of more than one rotary laser apparatuses causes a level sensor mounted on one construction machine to identify a wrong laser beam that should have been received by another construction machine, which leads to undesired functions or malfunctions of the construction machines.
In order to control more than one construction machines simultaneously without undesired functions or malfunctions, it is desirable that a single rotary laser apparatus is used to coordinate level settings. With the single rotary laser apparatus to perform the level settings for more than one elevations, however, the rotary laser apparatus must emit varied levels of laser beams toward the receiver construction machines in a single circular sweep. In the prior art rotary laser apparatus, an illuminator rotating at a revolution rate of several hundreds rmp emits laser beam to define a reference plane and a reference line. It is almost impossible to regulate a vertical position of the illuminator and let it emit laser beam in more than one directions at respectively varied elevations during such a high velocity operation. Thus, there is still not the construction machine control system where, simply with the single rotary laser apparatus, more than one construction machines can be under control and respectively level the land at different elevations from one another.
In a real leveling task, the land may originally be leveled, and sometimes, it is required to grade the land which is originally inclined to some extent. Additionally, it is often intended that an artificial inclination is created to drain the land, and in paving a road, also, the original geometry of the land is intentionally exploited into a reasonable slope or shaped into a slope as required for draining the land. In the conventional leveling work, after creating the leveled land by the construction machine control system, a terrain survey is carried out to shape the land with the desired slope.
In leveling the land originally flat, use of the above mentioned construction machine control system enables untrained workers to dedicate themselves to level the land without difficulty, but grading the land or creating the sloped land as desired is still a task only for experts. Evaluation of the finished slope also highly depends upon an expertise level of the worker. Thus, expertise of the worker is a major factor of attaining the finish as desired, and is also a factor of determining how long it takes to complete the task. In this regard, the prior art control system is still disadvantageous in that a management over accuracy in finishing the task and a management over scheduling the task are not easy jobs.
In some case, one construction site is to be leveled to create a terraced terrain of more than two sections at different elevations. For that purpose, there also arises a problem that after the rotary laser apparatus is used to level a section of land, settings of the rotary laser apparatus must be changed to level the remaining section of the land, and this is a complicated and annoying task.
The present invention is made to overcome the aforementioned disadvantages and problems. Accordingly, it is an object of the present invention to provide a solution that enables a single rotary laser apparatus to control more than one construction machines so that the construction machines can simultaneously level the land up or down to sections at different elevations, respectively. It is another object of the present invention to provide solutions that enable any worker to efficiently grade a slope or to shape the land into sloped terrain as desired regardless of an expertise level of the worker and enable more than one construction machines to simultaneously grade slopes at different inclinations, respectively, and to shape the land into different slopes, respectively.